Concept 13.2
Mode of Grouped Data
Source: NCERT Mathematics, Class 1010 minute lesson
Formal statement
The modal class is the class with the maximum frequency. Mode = l + ((f₁ − f₀) / (2f₁ − f₀ − f₂)) × h, where l is the lower limit of the modal class, h the class size, f₁ its frequency, and f₀, f₂ the frequencies of the classes before and after it.
The intuition
The mode is the most common value, so look for the tallest bar: that is the modal class. The formula then nudges the answer within that class.
It leans towards whichever neighbour is taller. If the class after is busier than the class before, the mode sits higher in the class.
The attention
Look for the highest frequency: the tallest bar.
3, 7, 12, 9, 4 in classes 0–10, …, 40–50
Look hereNot here
- Look here
- The highest frequency. The modal class is where the data is most crowded: frequency 12, the class 20–30.
- Not here
- The class with the largest values. 40–50 contains the biggest values, but only 4 of them. Mode is about how often, not how large.
- What it teaches
- Say what a statistic measures before you go looking for it.